The Monte and Chaco Regions of The Boyce Thompson Arboretum and Desert Legume Program Expedition

by Matthew B. Johnson

Figure 1. Tephrocactus aoracanthus, northwest of San Juan. MJB Johnson Argentina 29

picked up a rental vehicle and drove to our hotel in the city. Matthew B. Johnson Driving in Argentina, particularly in urban areas, is not for the Desert Legume Program timid. Boyce Thompson Arboretum and We visited a small nature preserve in the hills on the west side the University of Arizona of Mendoza for our first look at the of this region of 2120 East Allen Rd. the country. The vegetation in this part of the Monte Desert Tucson, AZ 85719 resembles the vegetation in parts of the Chihuahuan Desert of North America. predominate, with a variety of herba- ceous plants and smaller cacti. Many spring-flowering species Editor’s Note: This is an updated version of an article that previously were in bloom. cuneifolia, one of the South American appeared in Aridus, the Bulletin of The Desert Legume Program of Boyce creosote bushes in the was particularly abun- Thompson Arboretum and The University of Arizona, Issue 13:1, February dant. It is called “jarilla norte sur” after the north south orienta- 2001. tion of the foliage. Also in abundance was Zuccagnia punctata, “jarilla melosa”, a caesalpinioid legume that superficially resembles Larrea from a Argentina is a country of great natural beauty and distance. This attractive evergreen has of small diversity. Extending from north of the Tropic of Capricorn yellow flowers and resinous foliage with an aroma similar to to Tierra del Fuego, much of the country has a dry climate. that of spruce (Picea spp.). It typically grows 1-2 m high, Legumes are an important element of many communities, but in favorable sites may attain 4 m. Zuccagnia is an excellent particularly in the Chaco and Monte regions in the northwest, candidate for introduction as a low water-use landscape plant. the area that we planned a visit. The purpose of the trip was to Other legumes present included praecox (Cercidium observe and photograph the vegetation in a variety of habitats praecox subsp. glaucum). This subspecies tends to remain shrubby for assistance in further development of the Argentine plant unlike the widespread subsp. praecox. Senna aphylla is common exhibits at the Arboretum, to document information on many here. This attractive plant is leafless beyond the seedling stage, of the native legumes, and to make contacts with individuals for and resembles species of Ephedra (Ephedraceae) with its possible collaboration. numerous slender green stems. Senna aphylla has done well in On the first day of November, 2000, BTA and DELEP cultivation in southern Arizona and is beginning to be grown as Director Bill Feldman, BTA Horticulturist Jeff Petrie, and I a landscape plant. A shrubby algarrobo, flexuosa, Prosopi- departed Phoenix for Buenos Aires via Miami. We enjoyed a dastrum globosum, and a species of Adesmia were also found here. mild and sunny spring day in the Argentine capital as we visited Another interesting­ shrub at this site is Bougainvillea spinosa, in bookstores to seek out references on the flora of the country. the Nyctaginaceae, with spiny stems, reduced leaves and small A final flight took us to Mendoza, a pleasant city situated at yellow bracts subtending the flowers. Many of the other plants the base of the mountains in a large agricultural region. Rivers were recognizable as the same genera as plants found in dry flowing down from the provide water for irrigation. We regions of North America. Mr. Frederico Soria, a ranger at the preserve, assisted us with plant identification. The following day we headed west from Mendoza and up into the Andes. Ranges of steep and rugged mountains rise above arid valleys. Each turn in the road presented scenic views and changing geology. Larrea cuneifolia is replaced by as elevation increases. A notable in this area is Denmoza rhodacantha. In growth form it resembles some of the North American Ferocactus species. Though present at the nature preserve, this species grows larger in the more favorable condi- tions at higher elevations. Some hillsides supported hundreds of plants attaining heights up to 2 m. Several of the legumes we observed at the nature preserve the previous day were common here. Higher up we entered a dry grassland community with scattered shrubs. Immense snow-capped peaks tower above the landscape. Clouds were lowering and snow began to fall. A few Figure 2. The steep grades of Highway 7 near Mendoza, Argentina. Figure 1. Tephrocactus aoracanthus, northwest of San Juan. MJB The Andes Mountains rise in the distance. MJB kilometers from the border with Chile we turned off at Cerro 30 Desert Plants 31(1) October 2015

Aconcagua Provincial Park. At 6,962 m (22,834 ft), Aconcagua tive corkscrew-like fruits. Prosopis chilensis became increasingly is the highest point in the Americas. After a short hike near the common northward. The vegetation became denser with new park headquarters, the biting wind, freezing temperatures, and species appearing as we entered the Arid Chaco, a vast shrubby snow squalls hastened our return to Mendoza. woodland lying between the Monte Desert and the Semiarid We departed for San Juan and then north toward La Rioja. Chaco. We encountered numerous trees of Senegalia visco (Acacia The weather was mild with variable clouds. This vast desert visco) along drainages coming out of the mountains north of country felt familiar in many respects. Much of the area had Chepes. This is the largest acacia native to Argentina. It can received significant rainfall in previous months resulting in lush grow to 15 m (50 ft) high, is unarmed and has lacy foliage. vegetation and numerous wildflowers. The shrubs and many It is sometimes planted in plazas and along streets as a shade cacti were flowering as well. In addition to the widespread . The acacias and algarrobos were especially attractive with Parkinsonia praecox, and Senna aphylla, we saw the fresh, bright green, newly emerged foliage. Senegalia visco Mimosa ephedroides, another Ephedra mimic. Though it produces has been cultivated in Arizona under the mistaken identity of leaves under favorable conditions, for much of the year it is Acacia abyssinica. The original plants in the state were planted at

Figure 3. Zuccagnia punctata. Parque Nacional Sierra de las Qui- Figure 5. Parkinsonia praecox, east of San Juan. Photo: JMP jadas, San Luis. MBJ

Boyce Thompson Arboretum over 80 years ago. Lowering skies and rain showers greeted us as we headed west again into the Monte. At Valley of the Moon, in northern San Juan Province, we encountered intermittent fog, drizzle and a steady cold wind. It was quite a treat to see such an arid desert region under these conditions. Outside of La Rioja, in the rugged Sierra de Velasco we encountered a variety of legumes including Mimosa farinosa. This mimosa is a small to large shrub with small and relatively innocuous prickles. Senegalia furcatispina (), “garabato negro”, certainly deserves the name “barbed­ wire acacia” for its peculiar armament. The painfully sharp, opposed spines are set on short spurs along the stems and are particularly difficult to disentangle without being hooked Figure 4. Vachellia aroma, near San Juan. JMP by adjacent spines. This plant has done well in cultivation in southern Arizona and would be very effective if planted as a leafless, with unarmed, photosynthetic twigs. Another common security hedge. The rocky slopes support forests of and widespread legume is Prosopis torquata. This usually shrub- terscheckii (Trichocereus terscheckii), a large columnar cactus resem- by species has racemes of bright yellow flowers and distinc- bling the saguaro, Carnegiea gigantea, of the Sonoran Desert. The Johnson Argentina 31

slopes were covered with masses of spiny terrestrial bromeliads and these, together with the low but dense woody and often spiny vegetation, made walking around on the slopes challeng- ing. While the vegetation resembles Arizona in some respects, the ground bromeliands (Dyckia and Deuterocohnia) as well as an abundance of three species of epiphytic Tillandsia, and the presence of parrots, provided significant contrasts. The area around Aimogasta to the north of the Sierra de Velasco is particularly arid, receiving perhaps 100 mm of rain- fall per year. We traveled north towards Andagala, in Catamarca Province, along the west side of the massive Sierra de Ambato. An extensive salt pan, the Salar de Pipinaco, lies to the west at the lowest part of a vast basin. Skies were sunny and the wind was considerable. Yellow flowers of Vachellia aroma and white flower of Senegalia furcatispina provided color among the denser shrubby vegetation along the lower bajada. At this more northerly and warmer latitude, plants such as Parkinsonia praecox and Senna aphylla had mostly finished flowering. Several olive plantations have recently been planted in this area. Numerous broad, sandy arroyos drain the mountain range. These often support huge trees of Prosopis chilensis, some of which are up to 15 m (50 ft) tall with trunks a meter or more in diameter. Near Andagala the vegetation, dominated by Vachellia, Larrea, Prosopis and large Echinopsis, was especially reminiscent of that in parts of the Sonoran Desert. Heading back to the south, the wind had churned up an impressive dust storm. The sun faded to a pale disk in the brown haze and visibility was reduced to less than a kilometer as airborne sand snaked and rippled across the

Figure 6 (above). Tillandsia duratii, an epiphyte, is growing from Echinopsis terscheckii in the Sierra del Velasco. MBJ

Figure 7 (left). A long view of Sierra del Velasco. JMP 32 Desert Plants 31(1) October 2015

skies with intermittent drizzle. The Arid Chaco vegetation east of the city is a particularly dense thornscrub and in places is nearly impossible to penetrate due to the tangled thickets of spiny plants. As elsewhere, legumes were dominant, with Vach- ellia aroma, Senegalia furcatispina, Parkinsonia praecox subsp. prae- cox, Prosopis nigra, and Senna aphylla being particularly abundant. The rains had come early and with abundance this year and the forest canopy was in an advanced state of leaf development. An almost infinite variety of hues of green covered the slopes of the Sierra de Ancasti in the mountain Chaco forest. This subtropical forest includes many species that are partially or wholly deciduous during the drier winter months. Clouds and occasional light rain continued as we drove on towards Santiago del Estero. The Semiarid Chaco is a tropical/subtropical dry forest that covers much of the lowlands of northern Argentina to the east of the mountains, as well as parts of western Para- guay, southwest and adjacent Brazil. The forest contains a high diversity of species that are adapted to seasonal drought. Legumes are important elements of plant communities in the Semiarid Chaco. Morning broke over Santiago del Estero under a steady rain that increased in intensity as the hours passed. Water filled the streets and then covered many of the sidewalks. Shopkeep- ers struggled to keep the floodwater out of their stores. With water leaking through the floor of our vehicle, we managed to navigate the flooded streets to higher ground and made our way out of the city. The rain eased up as we drove south. A conspicuous legume in this area is Prosopis kuntzei, a distinctive tree that produces a dense canopy of photosynthetic twigs with highly reduced, drought-deciduous leaves. This interesting and attractive plant commonly grows to 8 m (25 ft) high. Prosopis kuntzei, along with several other members of the genus found in Argentina, is listed as a prohibited noxious weed by the USDA and may not be imported or grown in the U.S. Another Proso- pis species found in this region, though hardly conspicuous, is P. reptans var. reptans. This subshrub seems to prefer growing beneath trees where it seldom exceeds 60 cm in height. Proso- pis reptans var. reptans has tightly coiled pods like those of the Figure 8 (top). Senna aphylla in flower. MBJ closely related P. reptans var. cinerascens that occurs in southern Texas and northeastern Mexico. Figure 9 (bottom). Matt Johnson and Bill Feldman descend into a In northern Cordoba province we passed through an exten- canyon of Echinopsis terscheckii near Choya, east of Catamarca. sive area of salt lakes with surrounding halophytic vegetation. JMP On slightly higher terrain was a more diverse shrubby commu- nity dominated by Stetsonia coryne, a much-branched, candelabra- pavement. The dust storm passed and the sun dipped below the like cactus that attains the size of a small tree. A common name western horizon. The arid, moonlit landscape was permeated for the plant is “toothpick cactus”, referring to the notably long by a pleasant moist scent carried on the cool night air. Towering spines. Further south the terrain was rolling with areas of Proso- thunderheads to the east of La Rioja were illuminated by the pis and Vachellia. Other sites support magnificent savannahs bright moonlight and frequent lightning. of Trithrinax campestris. This exquisite fan palm, with glaucous We departed Catamarca the following morning under cloudy bluish leaves, seldom grows taller than 8 m (25 ft) and is worthy Johnson Argentina 33

Figure 10 (top). Opunitia quimilo, south of Santiago del Estero. In the far backround are the tips of multi- branched, candelabra-shaped Stetso- nia coryne, often called the toothpick cactus. JMP

Figures 11 and 12 (left). Trithrinax campestris, found growing nearly monotypically, forming a huge sa- vanna in northern Cordoba province. JMP of cultivation. The verdant terrain at the north end of the Sier- ably more rugged than the eastern side. Back down into woody ras de Cordoba is dominated by Prosopis chilensis and other trees. scrub again, a locally common legume is Vachellia atramentaria Legumes such as decorticans and acacias are common (Acacia atramentaria), a small-stature tree or large shrub. Along here. The rather dense understory supports many shrubs, vines the roadside we found Rhynchosia senna with attractive yellow and herbaceous plants. Several cacti and bromeliads are found flowers. in rocky areas. Sunny skies and a brisk wind welcomed us to San Luis Prov- We drove west from Cordoba into the mountains where ince. Shrubs of Erythrostemon gilliesii (Caesalpinia gilliesii) and Senna legumes are poorly represented, perennial bunchgrasses aphylla blazed with flowers along the highway. The Arid Chaco predominate, and fires are common. We stopped at the Andean scrub in this region is dominated by Parkinsonia praecox subsp. Condor preserve headquarters of Mr. Fabian Ramallo. Thanks praecox, Prosopis spp., Senna aphylla and Larrea divaricata. The only to his tireless efforts, this magnificent bird, once nearly extermi- larger cactus present is an occasional Cereus aethiops, “cardoncillo”. nated from these mountains, has made a successful comeback. This species seldom grows more than 4 m tall. Alongside the The western escarpment of the Sierras de Cordoba is consider- Sierra de San Luis, the downpour from a thunderstorm gave 34 Desert Plants 31(1) October 2015

way to a spectacular double rainbow, punctuated by lightning strikes. The sun, low on the cloudless western horizon, cast bril- liant light that illuminated raindrops on flowering patches of Hoffmannseggia glauca along the highway shoulders. Known as “porotrillo” in Argentina, this low­ growing, herbaceous legume is also native to the southwest U.S. and Mexico where it is called “hog potato” or “camote de raton”. The tuberous roots have been used as a source of food. A full moon rose above the Sierra de San Luis. The first stars appeared as the orange glow of the sunset faded in the west. An isolated thunderstorm to the south flickered with shades of pink and peach. We awoke in San Luis to rain showers followed by clearing skies. Traveling northwest, we came to the Sierra de las Quijadas. A national park preserves an extensive area of desert and scrub in and around this low mountain range. Here again, we found the vegetation lush and in flower due to the ample rains. Aver- Figure 13. Ramorinoa girolae, a papilionoid legume endemic to arid age yearly precipitation at the park is 300-400 mm (12-16 in.). regions of western Argentina. Sierra de las Quijadas National Park, The diverse shrub flora is dominated byLarrea cuneifolia. Several northwest of San Luis. MBJ smaller cacti are abundant and legumes are common. Adesmia triyuga is a spinescent shrub with yellow pea-like flowers. This diverse South American genus includes at least 225 species. Other familiar legumes here are Senegalia furcatispina, Parkinso- nia praecox (subsp. glauca), Prosopidastrum globosum, Senna aphylla and Zuccagnia punctata. Three species of Prosopis, P. chilensis, P. flexuosa and P. torquata, were seen. The “chañar”, Geoffroea decor- ticans, is present. This widespread, hardy and adaptable legume resembles species of Parknsonia, with photosynthetic bark and yellow flowers; though the flowers ofGeoffroea are pea-like. The specific epithet refers to the bark that decorticates in strips and patches. The fruit is unusual among legumes, consisting of a thin fleshy rind surrounding a single-seeded “pit”. When ripe, the fleshy exocarp is edible and has the flavor of ginger- bread. It is eagerly sought by wildlife and domestic stock, and Figure 14. Matt Johnson braces himself against winds gusting up to is employed in a variety of food and beverage applications in 60 mph in the Atuel River valley west of San Rafael. The Andes rise areas where it occurs. Cultivated plants have done very well sharply in the backround to the west. JMP in Arizona, though a tendency to spread by roots, eventually forming large thickets, is a potential drawback. We were excited to find Ramorinoa girolae growing on sandstone ledges above a canyon. This monotypic papilionoid legume is endemic to arid regions of western Argentina. A shrub or small tree, R. giro- lae forms a canopy of dense, green, spinescent twigs with tiny scale-like leaves and racemes of yellow flowers and woody pods. The contorted appearance of some of these plants suggests they are long-lived. Dead stems containing an unusual woody star-burst gall are sold as curios and the seeds are re ­ported to be used as a coffee substitute. Returning to San Luis, we headed south towards San Rafael. Extensive areas of dominate the landscape, with each plant consisting of hundreds of individual trunks connected by roots and forming scrubby, impenetrable, dome- Figure 15. Lathyrus macropus, “agua de nieve de la sierra”. MBJ Johnson Argentina 35

The skies had cleared except for a few clouds swirling around the summits of the rugged peaks. Brilliant ice fields shown in the sunlight. Cerro Sosneado, at 5,189 m (17,020 ft) was the highest peak visible. We ascended the Atuel Valley on a rather marginal road. Ice cold streams crossed our route to join the swift-flowing Río Atuel. We encountered a third creosote bush, Larrea nitida. Appearing similar to the others from a distance, this species has pinnate leaves. The valley narrowed and the vegetation took on a more xeric aspect. Though the sun was warm, a piercing cold gale buffeted us with gusts up to 100 kilometers per hour (60 mph), making photography extremely difficult. The wind pelted us with airborne sand and bits of plant debris. The frequent strong winds have shaped a fasci- nating community of cushion plants – the growing tips being pruned by the wind so that species with a more typical shrub- like growth form were shaped into tightly branched domes and mounds. Several legumes grew here including Ramorinoa girolae, a species of Adesmia and an herbaceous Astragalus. Also pres- ent was an as yet unidentified, low-growing herbaceous Senna with rather large leathery leaflets and showy yellow flowers. A most unexpected find wasLathyrus macropus, “agua de nieve de la sierra”. This robust her­baceous perennial with large leathery elliptic dark green leaves, trailing stems, and racemes of purple flowers, seemed oblivious to the wind and blowing sand. We headed north toward Mendoza. A huge wall of rock to the west flanked our route, rising abruptly from the lowlands and forming a spectacular backdrop with icy peaks reaching elevations of 7,000 m (20,000 ft). Back in Mendoza, we attend- Map 1. Argentina ed a conference on the conservation and sustainable use of Prosopis in South America. Our travels around Argentina covered 4,000 km (2,500 shaped thickets 30 m (100 ft) or more across. The vegetation miles) through seven provinces in eight days, with additional gradually changed to a shrubby grassland covering an exten- short trips out from Mendoza. A wealth of information was sive undulating plain. Prosopidastrum globosum, “caballo del diablo” obtained on individual plant species and the communities in is common here. This shrub grows to 2 m tall and has sharp- which they occur. Hundreds of slides documented the plants tipped, photosynthetic twigs, small leaves, and white flower and their habitats. This information will benefit both DELEP heads. A cold wind blew from the southwest as the sun set. and BTA. We are indebted to the many people who shared Heading west the next morning from San Rafael under a their time and knowledge with us. We especially thank Mariano high overcast, we came to the Sierra Pintada. The lower east- Cony and the personnel at CRICYT, and Frederico Soria. ern slopes support a dense population of Echinopsis candicans (Trichocereus candicans) forming clumps of thick, ultimately reclining stems. In the cool morning temperatures we were treated to a spectacular display of hundreds of large, white, funnel-shaped flowers arising from these cacti. Beyond this low mountain range the highway took us across a broad sandy valley with grasses and scattered shrubs. Prosopis alpataco formed hummocks to 5 m across and seldom more than a meter high. The sparse, newly emerging foliage could scarcely hide the intimidating spines, as thick as the twigs and up to 10 cm long. The snow-capped Andes loomed to the west. The South American Deserts Exhibit

Plans for creating the South American Deserts Exhibit north- east of Ayer Lake were underway as early as 1990. Matt Johnson visited South America three different times in the early 1990s, exploring both the Chaco and Monte regions on each trip. In 1993, he was instrumental in helping to create a document that would guide the creation of this new exhibit, further refined by the collective experience of Bill Feldman, Jeff Petrie, and Matt Johnson, realized from the 2000 expedition described in this article. Many of the very first South American accessions came from seed that Matt collected during the earlier expeditions. By 2001, planting in the new exhibit was well underway, and continued steadily for the next several years, including many new accessions later acquired as a result of contacts made during the 2000 expedition. Six large Echinopsis terscheckii cacti and other large columnar cactus species were planted in 2009, rounding out the South American exhibit with a hillside of these cacti, creating an effect that is similar to the way these cacti might be found in their native habitat in the Monte region of Argentina.

Figure 16 (right). Several Echinopsis terscheckii cacti in the fore- ground with the vernacular architecture of the quincho behind. KWS

Figure 17 (below). Bill Feldman contemplates the high point of the day’s climb in the Syunt-Khasardagh Zapovednik of Turkmenistan. Photo: A. Saparmuradov